Nano-optics is the study of optical phenomena and techniques on the nanometer scale, that is, near or beyond the diffraction limit of light. It is an emerging field of study, motivated by the rapid advance of nanoscience and nanotechnology which require adequate tools for fabrication, manipulation and characterization at this scale. The lecture provides a comprehensive overview of the theoretical and experimental concepts in nano-optics. It describes optical phenomena relevant to the nanoscale across many physical areas.